The overally objective is to examine the role of monoclonal cell populations in the origin and growth of atherosclerotic lesions in experimental animale and in man. Human studies will use the X-linked enzyme, Glucose-6-Phosphate Dehydrogenase, as a cellular marker for identification of monoclonal cell populations. The expression of certain genes associated with tumors will be examined in normal arterial wall, fatty streaks and atherosclerotic plaques as a test of the mutational theory of atherosclerosis. Intimal surfaces of aortas will be mapped to identify gross morphologic, histologic and histochemical characteristics of normal appearing intima and intimal lesions which have monoclonal characteristics. Animal studies will seek to further describe the hybrid hare as a promising model of human atherosclerosis. The lesions will be further studied for their clonal characteristics as well as histologic and histochemical features. Various dietary regimens will be employed to test the clonal selection theory. An immunofluorecence method for assessing isoenzyme characteristics in tissue sections will be developed.